JPH08205436A - motor - Google Patents

Abstract

PURPOSE: To obtain a motor having a permanent magnet embedded in the rotor in which the reluctance torque and the magnet torque can be utilized effectively. CONSTITUTION: The motor comprises an outer stator having a plurality of field sections 6 for applying a rotating field, and an inner rotor 3 where permanent magnets of the same number as the field sections 6 are embedded perpendicularly to the radial direction of rotor in the outer circumferential part of the rotor body 3a made of a high permeability material. Each permanent magnet 8 is cut at the opposite end parts thereof thus enlarging the interval between the end part 18 of respective permanent magnets 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor having a permanent magnet embedded in a rotor.

[0002]

2. Description of the Related Art Conventionally, there is known a motor with a permanent magnet in which a plurality of permanent magnets which are arranged orthogonally to the rotor radial direction are embedded in the outer peripheral portion of the rotor.

For example, the four permanent magnets 8 shown in FIG. 2 are embedded in the rotor 3 so that the S and N poles alternate. Then, an alternating current is caused to flow through the coil 10 of the stator 2 to generate a rotating magnetic field in the plurality of field portions 6, thereby utilizing the magnet attractive force and the repulsive force with the permanent magnet 8 in the rotor 3. The rotor 3 is rotating.

[0004]

In the above-mentioned conventional structure, the magnet torque is mainly used, and there is a problem that the torque becomes insufficient at high speed rotation.

In recent years, reluctance motors utilizing a magnetic path formed between magnetic salient pole portions of a rotor have attracted attention.

Generally, in the motor with a permanent magnet shown in FIG.
The magnetic flux of the field portion 6 easily passes through the rotor body 3a made of iron or the like having a high magnetic permeability, and the inductance Lq in the q-axis direction in the figure increases, while the magnetic permeability of the permanent magnet 8 decreases. For example, the inductance Ld in the d direction in the figure becomes small.

A motor utilizing reluctance torque is
The reluctance torque is generated by the difference between the inductances Lq and Ld, and thereby the rotational force is obtained.

However, in the above-mentioned conventional example, as shown in FIG. 2, between the adjacent end portions 18 of the plurality of permanent magnets 8 embedded in the rotor 3, only the space indicated by L'in the figure is obtained, and the magnetic flux is mainly generated. The magnetic path shown by P'in FIG. Here, the magnetic flux forms a magnetic path so as to be connected at the shortest distance, but the magnetic flux flowing in the region indicated by P ′ in the figure has a limit and is saturated immediately, so that the inductance Lq is made larger than that. It was not possible to make full use of reluctance torque.

The present invention, even if it is a motor with a permanent magnet,
An object of the present invention is to provide a motor that can effectively utilize reluctance torque as well as magnet torque.

[0010]

In order to achieve the above object, the present invention provides an outer side stator having a plurality of magnetic field portions for applying a rotating magnetic field and an outer peripheral portion of a rotor body made of a high magnetic permeability material. A rotor having an inner side in which the same number of permanent magnets as the field magnets are embedded so as to be orthogonal to the rotor radial direction, and each of the permanent magnets is formed in a shape in which both ends thereof are cut out, The feature is that the distance between the ends of each permanent magnet is widened.

Further, it is preferable that each permanent magnet is formed in a substantially trapezoidal shape that is convex in the centripetal direction of the rotor.

[0012]

The present invention having the above-described structure can perform the following operations. That is, although the magnetic path is formed so that the magnetic flux between the field parts of the stator is connected in the shortest distance, the magnetic flux flowing in the magnetic path indicated by P ′ in FIG. Resulting in. Therefore, by widening the width between the end portions of the adjacent permanent magnets, a magnetic path indicated by P in FIG. 1 passing between the end portions is formed, and a large amount of magnetic flux can be passed through the rotor body. .

Therefore, in the direction orthogonal to the permanent magnet, the permanent magnet is a low-permeability material, and it is difficult for the magnetic flux to pass therethrough, and the inductance Ld in the d direction in FIG. Since the magnetic flux easily passes in the direction in which the magnetic field is widened to become a magnetic convex pole, the inductance Lq in the q direction in the figure can be increased. As a result, the difference between the two inductances Ld and Lq can be increased,
The reluctance torque can be effectively used.

Therefore, according to the present invention, both reluctance torque and magnet torque can be effectively used, and as a result, a higher torque can be generated as compared with a motor using only magnet torque or reluctance torque, so that motor efficiency is improved. Performance improvements such as downsizing and downsizing can be realized.

If each of the permanent magnets is formed in a substantially trapezoidal shape that is convex in the centripetal direction of the rotor, it is possible to form a wide gap between the ends without reducing the magnetic field surface of the permanent magnet at a relatively low cost. You can

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention.

Inside the rotor 3 on the inner side, four permanent magnets S and N are arranged on the outer peripheral portion of the rotor main body 3a made of a high magnetic permeability material (iron material) and arranged at equal pitches orthogonal to each other in the radial direction. It is buried so that the poles are arranged alternately. The permanent magnet 8 is formed in a substantially trapezoidal shape having a notch 9 that is convex in the centripetal direction of the rotor 3, and the rotor body 3 is widened so as to widen the space 18 between the adjacent ends of each permanent magnet 8.
It is buried in a.

On the other hand, the stator 2 on the outer side is provided with four field portions 6, and an alternating current is applied to these coils 10 to generate a rotating magnetic field.

Since the rotor 3 has the rotor body 3a covered with the iron material of the high magnetic permeability material through which the magnetic flux of the field portion 6 easily passes, and the permanent magnet 8 of the low magnetic permeability material through which the magnetic flux does not pass easily, The d-axis direction orthogonal to the center of the permanent magnet 8 and the q-axis direction passing through the center of the end portion 18 that is deviated by an electrical angle of 90 degrees from each other are configured so that the inductances Ld and Lq are significantly different. .

That is, since the space 18 between the end portions shown in FIG. 1 is wide as shown by L in FIG. 1 and forms a magnetic salient pole, a magnetic path shown by P in the figure is formed inside the rotor 3. To be done. This is because when the magnetic path indicated by P ′ is saturated, a magnetic path for further flowing magnetic flux is formed.

In such a structure, in the d-axis direction of FIG.
While d can be made extremely small, in the q-axis direction in which the electrical angle is deviated by 90 degrees from the d-axis, a magnetic path is formed to facilitate passage of magnetic flux, the inductance Lq increases, and the difference between the inductances Ld and Lq increases. Therefore, the reluctance torque can be effectively used.

Further, a plurality of field portions 6 in the stator 2
The rotor 3 can be rotated by the magnet attractive force or repulsive force generated between the rotating magnetic field generated by the rotating magnet and the permanent magnet 8 in the rotor 3, and the magnet torque can be effectively used.

The characteristics of the motor using the reluctance torque and the magnet torque are expressed by the basic voltage equation (1) converted on the dq coordinate axes. Further, the torque T is expressed by the equation (2) from the equation (1).

[0024]

[Equation 1]

However, Vd, Vq: d and g axis components of armature voltage R: resistance equivalent to field winding 1 p: differential operator (p = d / dt) ω: electrical angular velocity id, iq: d , Q-axis current Pn: number of pole pairs φa: magnet magnetic flux Ld, Lq: d, inductance in q-axis direction That is, the q-axis inductance Lq and the d-axis inductance Ld by the permanent magnet 8 which is a material having a small magnetic permeability.
The difference between the two values causes the inductance difference represented by Ld and Lq to increase, effectively generating the reluctance torque shown in the second term of the equation (2). Further, the magnet torque shown in the first term of the equation (2) is applied, and the torque is obtained by both torques.

In the above embodiment, the rotor unit 3 has its rotational position and rotational frequency detected in advance by a hall element, an encoder or the like, and the phase of the alternating current flowing through the coil 10 of the field unit 6 of the stator 2 is , So that a large combined torque of the reluctance torque and the magnet torque can be obtained, it is supplied so as to have a peak at a position shifted by θ = π / 8 (22.5 degrees) in electrical angle from the q-axis.

In the above embodiment, an example using four permanent magnets 8 is shown, but other number of multipoles may be used. Further, in the above embodiment, the current phase is given by being shifted by θ = π / 8 (22.5 degrees).
θ does not have to be π / 8, and may be adjusted according to the rotor structure and current value. Furthermore, although the permanent magnet 8 has a substantially trapezoidal shape having the cutout portion 9 in the above embodiment, the cutout portion 9 may have a curved cutout shape. That is, the present invention is not limited to the above embodiments, and various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

[0028]

According to the present invention, not only the magnet torque but also the reluctance torque can be effectively utilized, and it is possible to provide a permanent magnet embedded type motor which outputs a large torque with a relatively simple structure.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional example.

[Explanation of symbols]

 2 stator 3 rotor 3a rotor body 6 field part 8 permanent magnet 9 notch part 10 coil 18 between end parts q q axis d d axis

Claims (2)

[Claims] 1. An outer side stator having a plurality of magnetic field portions for giving a rotating magnetic field, and an outer peripheral portion of a rotor body made of a high magnetic permeability material, the same number of the magnetic field portions being orthogonal to the rotor radial direction. The inner side rotor in which the permanent magnets are embedded is formed, and each of the above-mentioned permanent magnets is formed in a shape in which both ends thereof are cut out to widen the interval between the end portions of each of the permanent magnets. And a motor. 2. The motor according to claim 1, wherein each permanent magnet is formed in a substantially trapezoidal shape that is convex in the centripetal direction of the rotor.